Page:Popular Science Monthly Volume 90.djvu/893

 Popular Science Monthly

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���Crude carbolic acid plant. Phenols, cresols, xylols are washed with caustic soda. The phenol is freed from soda with acids

Coal tar dyes lend themselves so easily to coloring all substances capable of being colored that they are only too frequently abused. The illustration on page 875 shows a doll made by Prof. D. R. Hodgdon, who wished to call attention to the deleteri- ous use of aniline dyes in candy. Miss F. P. Sweets (Fraudulent Poisonous) con- tains poisons extracted from cheap confec- tions, such as lollypops and all-day-suckers. The glue which holds her hair on, the brilliant pink dress and green stockings, the copper on her knife blade, and the lampblack on her shiny shoes are all right in their place, but surely that place is not a child's stomach.

Although an Eng- lishman discovered the first coal tar dye, the German and not the English developed his dis- covery commercial- ly. They succeeded so well that they destroyed the nat- ural dye industry. Then Indiasuddenly found that her in- digo plantations were ruined. So cochineal, and min- eral dyes, like Prus- sian blue and chrome yellow, have been rapidly giving place to the modern syn-

���Huge benzol stills. The apparatus at the right is an agitator in which benzol is washed with sulphuric acid before entering the stills

��From the refining stills, 71 and 72, the phenol passes into the cooling tanks above, and then into the large receivers below

thetic dyes, now prepared from coal tar. An average tar yields seventy per cent of pitch and only six per cent of materials useful in making dyes. In the United States, ninety per cent of the tar goes to make better roads and better roofs, and also for the manufacture of creosote oil, naphthalene and other profitable products. After leaving coal tar, the next station is benzol. Benzol is an extremely inflamma- ble, colorless liquid obtained as previously stated, by the destructive distillation of coal tar. It is the basic product for the manufacture of ani- line colors and also cheap varnishes. It is used for many other purposes, chief among them being the manufacture of explosives.

Before the Euro- pean war, the nor- mal production of benzol in the United States was approxi- mately 3,000,000 gallons annually. Since the war, many steel companies, and other similar indus- tries, which could recover benzol from their other opera- tions, have been do- ing so. Result — in 1916, upwards of 15,000,000 gallons were produced. If every man, woman

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